Claim donkey continually grazed (10)

I believe the answer is:

asseverate

I'm a little stuck... Click here to teach me more about this clue!

'claim' is the definition.
(I've seen this before)

'donkey continually grazed' is the wordplay.
'donkey' becomes 'ass' (I've seen this before).
'continually' becomes 'ever' (I've seen this in other clues).
'grazed' becomes 'ate' (I am not sure about this - if you are sure you should believe this answer much more).
'ass'+'ever'+'ate'='ASSEVERATE'

Can you help me to learn more?

(Other definitions for asseverate that I've seen before include "State categorically" , "Swear" , "Solemnly say" , "Solemnly declare" , "Claim" .)

I've seen this clue in The Telegraph.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.